Aren
/
NetBSD
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix a deadlock where one thread exits, enters fstrans_lwp_dtor() 

and wants fstrans_lock.  This thread holds the proc_lock.
Another thread holds fstrans_lock and runs pserialize_perform().
As the first thread holds the proc_lock, timeouts are blocked and
the second thread blocks forever in kpause().

Change fstrans_lwp_dtor() to invalidate, but not free its info
structs.  No need to take fstrans_lock.

Change fstrans_get_lwp_info() to reuse invalidated info before
trying to allocate a new one.
This commit is contained in:
hannken 2014-04-15 09:50:45 +00:00
parent 05b3bfa0ba
commit 2f1e07219a
1 changed files with 20 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
sys/kern/vfs_trans.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: vfs_trans.c,v 1.29 2013/11/23 13:35:36 christos Exp $ */
/* $NetBSD: vfs_trans.c,v 1.30 2014/04/15 09:50:45 hannken Exp $ */
/*-
* Copyright (c) 2007 The NetBSD Foundation, Inc.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.29 2013/11/23 13:35:36 christos Exp $");
__KERNEL_RCSID(0, "$NetBSD: vfs_trans.c,v 1.30 2014/04/15 09:50:45 hannken Exp $");
/*
* File system transaction operations.
@ -82,7 +82,6 @@ static kcondvar_t fstrans_count_cv; /* Fstrans or cow count changed. */
static pserialize_t fstrans_psz; /* Pserialize state. */
static LIST_HEAD(fstrans_lwp_head, fstrans_lwp_info) fstrans_fli_head;
/* List of all fstrans_lwp_info. */
static pool_cache_t fstrans_cache; /* Pool of struct fstrans_lwp_info. */
static void fstrans_lwp_dtor(void *);
static void fstrans_mount_dtor(struct mount *);
@ -110,8 +109,6 @@ fstrans_init(void)
cv_init(&fstrans_count_cv, "fstcnt");
fstrans_psz = pserialize_create();
LIST_INIT(&fstrans_fli_head);
fstrans_cache = pool_cache_init(sizeof(struct fstrans_lwp_info), 0, 0,
0, "fstrans", NULL, IPL_NONE, NULL, NULL, NULL);
}
/*
@ -122,17 +119,16 @@ fstrans_lwp_dtor(void *arg)
{
struct fstrans_lwp_info *fli, *fli_next;
mutex_enter(&fstrans_lock);
for (fli = arg; fli; fli = fli_next) {
KASSERT(fli->fli_trans_cnt == 0);
KASSERT(fli->fli_cow_cnt == 0);
if (fli->fli_mount != NULL)
fstrans_mount_dtor(fli->fli_mount);
fli_next = fli->fli_succ;
LIST_REMOVE(fli, fli_list);
pool_cache_put(fstrans_cache, fli);
fli->fli_mount = NULL;
membar_sync();
fli->fli_self = NULL;
}
mutex_exit(&fstrans_lock);
}
/*
@ -237,7 +233,21 @@ fstrans_get_lwp_info(struct mount *mp, bool do_alloc)
}
}
if (fli == NULL) {
fli = pool_cache_get(fstrans_cache, PR_WAITOK);
mutex_enter(&fstrans_lock);
LIST_FOREACH(fli, &fstrans_fli_head, fli_list) {
if (fli->fli_self == NULL) {
KASSERT(fli->fli_trans_cnt == 0);
KASSERT(fli->fli_cow_cnt == 0);
fli->fli_self = curlwp;
fli->fli_succ = lwp_getspecific(lwp_data_key);
lwp_setspecific(lwp_data_key, fli);
break;
}
}
mutex_exit(&fstrans_lock);
}
if (fli == NULL) {
fli = kmem_alloc(sizeof(*fli), KM_SLEEP);
mutex_enter(&fstrans_lock);
memset(fli, 0, sizeof(*fli));
fli->fli_self = curlwp;